Thanks for the hint with the off-canvas. I have turned it off in the template style settings under navigation and now the second menu on mobile view is gone.
I was trying out the contact form, unfortunately the Purity IV Contact template doesnt show the subject field, therefore any contact request cant be send as it fails the validation.
<joomla root>\templates\ja_purity_iv\html\com_contact\contact\default_form.php
I added below code on row 45
<div class="form-group contact-sub row mb-3">
<div class="col-sm-12">
<?php echo preg_replace($regex, $label, $this->form->getLabel('contact_subject'), 1); ?>
<?php echo preg_replace($regex, $input, $this->form->getInput('contact_subject')); ?>
</div>
</div>